Passive heat-dissipating fan system and electronic system containing the same

ABSTRACT

A passive heat-dissipating fan system comprises an air-providing device, a cold-end passive heat-dissipating assembly, a hot-end passive heat-dissipating assembly, a separation device capable of guiding airflow to the cold-end and hot-end passive heat-dissipating assemblies, and a cooling device which is disposed in the separation device and has cold and hot ends. When the airflow from the air-providing device passes through the separation device and cooling device, airflow from the air-providing device is separated and then partially directed to the cold-end passive heat-dissipating assembly and partially directed to the hot-end passive heat-dissipating assembly respectively, expelling the heated airflow to an exterior of an electronic system. Because the temperature of the airflow passing through the cold-end passive heat-dissipating assembly is higher than that of dew point of air, the airflow passing through the cold-end passive heat-dissipating assembly can dissipate the heat generated by an electronic element without producing dew.

BACKGROUND

The invention relates to a passive heat-dissipating fan system, and inparticular to a passive heat-dissipating fan system having a coolingdevice with a cold end and a hot end, and using a separation device todirect airflow to the cold end and the hot end of the cooling device todissipate heat from a heat source and expel waste heat in an electronicsystem.

In general, a fan comprises an impeller and a motor connected to theimpeller. The motor is actuated by an electric power system to rotatethe impeller to generate airflow to dissipate heat from a heat source.The number of the fans depends on the sites of heat sources located inan electronic system. Thus, when more heat sources are located atdifferent sites in the electronic system, more motors and power arenecessarily increased.

In FIG. 1, an electronic system 1 comprises an electronic element 2(e.g. a processor), a cooling device 3 (e.g. a thermal electric cooleror a thermoacoustic cooler) disposed on the electronic element 2, and afin structure 33 disposed on the cooling device 3. The cooling device 3has two ends 31 and 32 contacting the electronic element 2 and the finstructure 33, respectively. When the cooling device 3 is actuated by anelectric power system (not shown), the end 31 of the cooling device 3becomes a cold end, absorbing heat from the heated electronic element 2and transferring heat toward the end 32 of the cooling device 3, and theend 32 of the cooling device 3 becomes a hot end, transferring heat tothe fin structure 33. When heat is dissipated from the fin structure 33,the waste heat still exists in the electronic system 1, which increasesthe working temperature and is easy to result in failure or malfunctionof the electronic element 2 or other elements in the electronic system1. On the other hand, when the temperature thereof decreases to the dewpoint or lower, water drops begin to condense on the cold end 31 of thecooling device 3; thus, the electronic element 2 and other elements maybe damaged.

To overcome the described problem, the invention provides a passiveheat-dissipating fan system to quickly dissipate heat from electroniccomponents of the electronic system and expel waste heat to the exteriorenvironment.

SUMMARY

The invention provides a passive heat-dissipating fan system fordissipating heat from electronic components to the exterior environment.The passive heat-dissipating fan system comprises an air-providingdevice, a cold-hot separation assembly connected to the air-providingdevice, at least one hot-end passive heat-dissipating assembly connectedto the cold-hot separation assembly, and at least one cold-end passiveheat-dissipating assembly connected to the cold-hot separation assembly.When the airflow from the air-providing device passes through thecold-hot separation assembly, airflow from the air-providing device isseparated and partially directed to the cold-end passiveheat-dissipating assembly and partially directed to the hot-end passiveheat-dissipating assembly.

The air-providing device comprises an active fan and an air-providingpipe connected to the active fan. The cold-hot separation assemblycomprises a separation device having a separation element therein and acooling device with a cold end and a hot end. The cooling device isconnected to the separation element and the cold and hot ends arerespectively disposed on both sides of the separation element. A hot-endchamber and a cold-end chamber are defined in the separation device bythe separation element and the cooling device, wherein the hot end ofthe cooling device is disposed in the hot-end chamber and the cold endof the cooling device is disposed in the cold-end chamber. The hot-endpassive heat-dissipating assembly is connected to the hot-end chamber,and the cold-end passive heat-dissipating assembly is connected to thecold-end chamber. The hot-end passive heat-dissipating assemblycomprises a hot-end pipe and a hot-end passive fan, and the hot-end pipehas two ends connected to the hot-end chamber and the hot-end passivefan, respectively. The cold-end passive heat-dissipating assemblycomprises a cold-end pipe and a cold-end passive fan. The cold-end pipehas two ends connected to the cold-end chamber and the cold-end passivefan, respectively.

The heat dissipated from the cooling device is carried away by theairflow traveling to the hot-end dissipating assembly and is expelled tothe exterior of the electronic system by the hot-end pipe. Thehigh-temperature airflow can further rotate the hot-end passive fan;thus the airflow circulation in the electronic system can be increased.

The airflow passing through the cold-end chamber has lower temperatureand travels to the cold-end dissipating assembly to dissipate heat froma heat source.

DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is a schematic view of an electronic system equipped with aconventional dissipating device.

FIG. 2 is a schematic view of an electronic system equipped with apassive heat-dissipating fan system of the invention.

FIG. 3 is a partially enlarged perspective view of the passiveheat-dissipating fan system of the invention.

FIG. 4 is a side view of FIG. 3.

DETAILED DESCRIPTION

In FIG. 2, an electronic system 1 of the invention comprises a housing100 and a passive heat-dissipating fan system 4 disposed in the housing100, at least one electronic element 2′ disposed in the housing 100, andat least one fin structure 21 disposed on one surface of the electronicelement 2′. The passive heat-dissipating fan system 4 comprises anair-providing device 41 disposed on one side of the housing 100, aseparation device 42 (shown by dotted circle) connected to theair-providing device 41, at least one cold-end passive heat-dissipatingassembly 43 connected to one side of the separation device 42, at leastone hot-end passive heat-dissipating assembly 44 connected to one sideof the separation device 42, a cooling device 45 disposed in theseparation device 42 (shown in FIG. 4). In this embodiment, two cold-endpassive heat-dissipating assemblies 43 and one hot-end passiveheat-dissipating assembly 44 are disclosed.

The air-providing device 41 comprises an active fan 411 and anair-providing pipe 412 connected to the active fan 411. The active fan411, e.g. an axial fan or a centrifugal fan, can be driven to rotate bya power supplier. High pressure airflow generated by the active fan 411is transmitted to the cooling device 45 disposed in the separationdevice 42 via the air-providing pipe 412.

In FIGS. 3 and 4, the separation device 42 comprises a separationelement 421 therein. The cooling device 45 has a cold end 450 c and ahot end 450 h disposed on both sides of the separation element 421,respectively. In this embodiment, the cooling device 45 is a heatdissipation device, e.g., a thermal electric cooler or a thermoacousticcooler, using the cold-hot separation technique to dissipate heat. Ahot-end fin structure 451 and a cold-end fin structure 452 are disposedon the surfaces of the hot and cold ends 450 h and 450 c of the coolingdevice 45, respectively. By connecting the cooling device 45 to theseparation element 421, the cold and hot ends 450 c and 450 h arerespectively disposed on both sides of the separation element 421; thus,a hot-end chamber 422 and a cold-end chamber 423 can be defined in theseparation device 42 by the separation element 421 and the coolingdevice 45.

In FIG. 2, the cold-end passive heat-dissipating assembly 43 comprises acold-end pipe 431 and a cold-end passive fan 432. The cold-end pipe 431has two ends connected to the cold-end chamber 423 and the cold-endpassive fan 432, respectively. The cold-end passive fan 432 can be amotor-free axial fan or a motor-free centrifugal fan disposed on the finstructure 21. Alternatively, the cold-end passive fan 432 can directlyblow the electronic element 2′.

The hot-end passive heat-dissipating assembly 44 comprises a hot-endpipe 441 and a hot-end passive fan 442. The hot-end pipe 441 has twoends connected to the hot-end chamber 422 and the hot-end passive fan442, respectively. The hot-end passive fan 442 can be a motor-free axialfan or a motor-free centrifugal fan disposed on one side of the housing100 to expel the waste heat from the hot-end chamber 422 to theexterior.

When the air-providing device 41 operates, air is drawn into theinterior of the housing 100 by the air-providing device 41 andpressurized. The pressurized air is transmitted to the cooling device 45disposed in the separation device 42 via the air-providing pipe 412.Because the hot-end chamber 422 and the cold-end chamber 423 defined inthe separation device 42 are formed by the separation element 421 andthe cooling device 45, the pressurized air is substantially divided intotwo parts: one part passes through the hot-end fin structure 451disposed on the hot end 450 h and enters the hot-end chamber 422, andthe other part passes through the cold-end fin structure 452 disposed onthe cold end 450 c of the cooling device 45 and enters the cold-endchamber 423. The pressurized air passing through the hot-end chamber 422has higher temperature and is transmitted via the hot-end pipe 441 todrive the hot-end passive fan 442. The pressurized air passing throughthe cold-end chamber 423 has lower temperature and is transmitted viathe cold-end pipe 431 to drive the cold-end passive fan 432.

The waste heat from the cooling device 45 is carried away by the airflowwhich passes through the hot-end fin structure 451 and exhausted to theexterior of the electronic system 1 by the hot-end passive fan 442.Moreover, the high-temperature airflow can further rotate the hot-endpassive fan 442, and thus the airflow circulation in the housing 100 canbe increased. The low-temperature airflow passing through the cold-endfin structure 452 flows toward the fin structure 21 disposed on theelectronic element 2′ via the cold-end passive fan 432; thus, heat fromthe electronic element 2′ can be rapidly dissipated. Due to the lowtemperature airflow passing through the dissipating fin structure 21being higher than that of the cold end 450 c of the cooling device 45,phenomenon such as dew accumulation can be prevented.

While the invention has been described with respect to preferredembodiment, it is to be understood that the invention is not limitedthereto, but, on the contrary, is intended to accommodate variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A passive heat-dissipating fan system, comprising: an air-providingdevice; a cold-hot separation assembly connected to the air-providingdevice; at least one hot-end passive heat-dissipating assembly connectedto the cold-hot separation assembly; and at least one cold-end passiveheat-dissipating assembly connected to the cold-hot separation assembly,wherein when an airflow from the air-providing device passes through thecold-hot separation assembly, the airflow is separated, and directed tothe cold-end passive heat-dissipating assembly and the hot-end passiveheat-dissipating assembly, respectively.
 2. The passive heat-dissipatingfan system as claimed in claim 1, wherein the air-providing devicecomprises an active fan and an air-providing pipe connected to theactive fan, and the active fan comprises an axial fan or a centrifugalfan.
 3. The passive heat-dissipating fan system as claimed in claim 1,wherein the cold-hot separation assembly comprises a separation devicehaving a separation element therein and a cooling device having a coldend and a hot end, wherein the cooling device is connected to theseparation element and the cold and hot ends are respectively disposedon both sides of the separation element, and a hot-end chamber and acold-end chamber are defined in the separation device by the separationelement and the cooling device, wherein the hot end of the coolingdevice is disposed in the hot-end chamber and the cold end of thecooling device is disposed in the cold-end chamber.
 4. The passiveheat-dissipating fan system as claimed in claim 3, wherein the coolingdevice comprises a thermal electric cooler or a thermoacoustic cooler.5. The passive heat-dissipating fan system as claimed in claim 3,wherein the hot-end passive heat-dissipating assembly is connected tothe hot-end chamber, and the cold-end passive heat-dissipating assemblyis connected to the cold-end chamber.
 6. The passive heat-dissipatingfan system as claimed in claim 5, wherein the hot-end passiveheat-dissipating assembly comprises a hot-end pipe and a hot-end passivefan, and the hot-end pipe has two ends connected to the hot-end chamberand the hot-end passive fan, respectively.
 7. The passiveheat-dissipating fan system as claimed in claim 6, wherein the hot-endpassive fan comprises a motor-free axial fan or a motor-free centrifugalfan.
 8. The passive heat-dissipating fan system as claimed in claim 5,wherein the cold-end passive heat-dissipating assembly comprises acold-end pipe and a cold-end passive fan, wherein the cold-end pipe hastwo ends connected to the cold-end chamber and the cold-end passive fan,respectively.
 9. The passive heat-dissipating fan system as claimed inclaim 8, wherein the cold-end passive fan comprises a motor-free axialfan or a motor-free centrifugal fan.
 10. The passive heat-dissipatingfan system as claimed in claim 3 further comprising a hot-end finstructure disposed on a surface of the hot end of the cooling device.11. The passive heat-dissipating fan system as claimed in claim 3further comprising a cold-end fin structure disposed on a surface of thecold end of the cooling device.
 12. An electronic system with a passiveheat-dissipating fan system, comprising: a housing; an air-providingdevice disposed in the housing; a cold-hot separation assembly connectedto the air-providing device; at least one hot-end passiveheat-dissipating assembly connected to the cold-hot separation assembly;and at least one cold-end passive heat-dissipating assembly connected tothe cold-hot separation assembly; and at least one electronic elementcorresponding to the cold-end passive heat-dissipating assembly, whereinwhen an airflow from the air-providing device passes through thecold-hot separation assembly, the airflow is separated, and thenpartially directed to the cold-end passive heat-dissipating assembly andpartially directed to the hot-end passive heat-dissipating assembly. 13.The electronic system as claimed in claim 12, wherein the hot-endpassive heat-dissipating assembly comprises a hot-end pipe and a hot-endpassive fan, wherein the hot-end pipe has two ends connected to thecold-hot separation assembly and the hot-end passive fan, respectively;and the cold-end passive heat-dissipating assembly comprises a cold-endpipe and a cold-end passive fan, wherein the cold-end pipe has two endsconnected to the cold-hot separation assembly and the cold-end passivefan, respectively.
 14. The electronic system as claimed in claim 13,wherein the hot-end passive fan comprises a motor-free axial fan or amotor-free centrifugal fan, and the cold-end passive fan comprises amotor-free axial fan or a motor-free centrifugal fan.
 15. The electronicsystem as claimed in claim 12, wherein the air-providing devicecomprises an active fan and an air-providing pipe connected to theactive fan, and the active fan comprises an axial fan or a centrifugalfan.
 16. The electronic system as claimed in claim 12, wherein thecold-hot separation assembly comprises a separation device having aseparation element therein and a cooling device having a cold end and ahot end, wherein the cooling device is connected to the separationelement and the cold and hot ends are respectively disposed on bothsides of the separation element, and a hot-end chamber and a cold-endchamber are defined in the separation device by the separation elementand the cooling device, wherein the hot end of the cooling device isdisposed in the hot-end chamber and the cold end of the cooling deviceis disposed in the cold-end chamber.
 17. The electronic system asclaimed in claim 16, wherein the cooling device comprises a thermalelectric cooler or a thermoacoustic cooler.
 18. The electronic system asclaimed in claim 16, wherein the hot-end passive heat-dissipatingassembly is connected to the hot-end chamber, and the cold-end passiveheat-dissipating assembly is connected to the cold-end chamber.
 19. Theelectronic system as claimed in claim 16 further comprising a hot-endfin structure disposed on a surface of the hot end of the coolingdevice, and a cold-end fin structure disposed on a surface of the coldend of the cooling device.
 20. The electronic system as claimed in claim12 further comprising a fin structure disposed on a surface of theelectronic element.